Measurement apparatus and method for the communication of an idle mode device having low mobility in a mobile communication system

ABSTRACT

The present invention defines an efficient measurement method for idle mode M2M/MTC device with low/no mobility in a mobile communication system. An example of the mobile communication system to which the present invention is application is 3GPP UMTS mobile communication system and 3GPP LTE/LTE-A mobile communication system as the next generation mobile communication system under discussion in 3GPP.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 16/401,556, filed on May 2, 2019, which is a continuationapplication of a U.S. National Stage application Ser. No. 13/521,511,filed on Jul. 11, 2012, which has issued as U.S. Pat. No. 10,313,959 onJun. 4, 2019, and is based on and claims priority under 35 U.S.C. § 371of an International Application filed on Jan. 13, 2011 and assignedapplication number PCT/KR2011/000245, which was based on and claimed thebenefit of a Korean Patent Application number 10-2010-0004052, filed onJan. 15, 2010, in the Korean Intellectual Property Office, thedisclosure of each of which is incorporated by reference herein in itsentirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a measurement apparatus and method of amobile communication system and, in particular, to a measurementapparatus and method for communication of a low mobility device.

Description of the Related Art

Mobile communication systems have developed to provide the subscriberswith voice communication services on the move. With the advance oftechnologies, the mobile communications have been evolved to supporthigh speed data communication services as well as the standard voicecommunication services. Recently, as one of the next generationUniversal Mobile Telecommunication System (UMTS) mobile communicationsystem, Long Term Evolution (LTE) is on the standardization by the 3rdGeneration Partnership Project (3GPP). LTE is a technology designed toprovide high speed packet-based communication of up to 100 Mbps higherthan the data rate of the legacy system.

Meanwhile, many discussions are being conducted for providing diverseservices in the UMTS/LTE mobile communication system. M2M/MTC is one ofthe representative technologies under discussion. Machine ToMachine/Machine Type Communication (M2M/MTC) denotes the communicationbetween electronic devices or between electronic device and data serverthrough a mobile communication network. The M2M/MTC technology isapplicable to the automotive telematics, logistics management,intelligent metering system, remote asset management system,Point-Of-Sale (POS), and security-related field. The M2M/MTC device(e.g. metering system) is likely to have low mobility as compared to thenormal mobile phone. There is therefore a need of modifying theprocedures specified for the normal mobile phones operating in themobile communication system.

FIG. 1 is a diagram illustrating a structure of a 3GPP UMTS mobilecommunication system.

Referring to FIG. 1, the User Equipment (UE) 101 is a terminal or asubscriber connected to a Node B (NB) 105 through a radio link toparticipate in radio communication. The NBs 105, 110, 115, 120, 125, or130 are the radio base station apparatuses directly responsible forcommunication with UEs and manage the corresponding cells. The RadioNetwork Controllers (RNCs) 140 and 150 control the NBs and radioresources. The RNCs 140 and 145 connect to the Packet Switched or PacketService (PS) network via the Serving GPRS Support Node (SGSN) 150. TheRNCs 140 and 145 and SGSN 150 are connected through Iu-PS interface andexchange packet-switched control signal. The SGSN 150 is responsible forvarious control functions and mobility management for the idle modeterminals. The SGSN 150 is also responsible for the data related to thesubscriber's service billing and controls communication to exchange datawith the UE 101 through the Serving RNC (SRNC) of the UE 101. TheServing Gateway (S-GW) 160 is the apparatus for providing data bearerand allocates and releases the data bearer under the control of the SGSN150.

FIG. 2 is a diagram illustrating a structure of the 3GPP LTE mobilecommunication system.

Referring to FIG. 2, the radio access network of the LTE mobilecommunication system includes Evolved Node Bs (eNB or Node B) 205, 210,215, and 220; Mobility Management Entity (MME) 225; and Serving Gateway(S-GW) 230. The User Equipment (UE) 235 connects to an external networkthrough the eNB 205 and S-GW 230. Each of the eNBs 205 corresponds to anentity combining the legacy Node B and RNC of the UMTS system. The UE235 connects to one of the eNBs 205 to 220 through a radio channel andeach eNB is responsible for the complicated functions as compared to thelegacy Node B. In LTE, since all user traffics including the traffic ofreal time service such as Voice over IP (VoIP) are served through ashared channel, there is a need of a device for collecting the statusinformation of the UEs to schedule the UEs, and the eNBs 205 to 220 areresponsible for this function. The eNBs 205 to 220 are also responsiblefor controlling radio resource of the corresponding cells. Typically, aneNB controls plural cells. In order to secure the data rate of up to 100Mbps, LTE adopts Orthogonal Frequency Division Multiplexing (OFDM) asradio access technology on the 20 Mhz bandwidth. LTE also adoptsAdaptive Modulation and Coding (AMC) for determining the modulation andchannel coding rate in adaptation to the channel condition of the UE.The S-GW 230 is the entity for providing data bearers so as to establishor release data bearer under the control of the MME 225. The MME 225 isthe entity responsible for various control functions and mobilitymanagement of the idle mode UEs, in connection with the eNBs.

FIGS. 3a to 3c are diagrams illustrating the idle mode UE managementmethod in the 3GPP UMTS/LTE mobile communication system.

Referring to FIGS. 3a to 3c , reference number 301 of FIG. 3a denotes alegacy UE such as mobile phone, reference number 302 denotes an eNB ofthe LTE mobile communication system, and reference number 303 denotes anRNC of the UMTS mobile communication system. In FIG. 3a , referencenumbers 311 and 313 denote signaling RNC/eNB-related information forsupporting efficient management of the legacy idle mode UEs in theUMTS/LTE mobile communication system. Reference numbers 321 to 327 ofFIG. 3b denote details of measurement method of the legacy UE in theUMTS mobile communication system, and reference number 331 to 335 ofFIG. 3c denote details of the measurement method of the legacy UE in theLTE/UMTS mobile communication system. The measurement method denoted byreference numbers 331 to 335 of FIG. 3c can be applied to the UMTSmobile communication system as well as the LTE mobile communicationsystem, and the UMTS system signals the indication informationindicating whether the measurement method denoted by reference numbers321 to 327 or the measurement method denoted by reference numbers 331 to335 is applied and configuration information related thereto.

In the UMTS mobile communication system, the RNC configures theinformations for supporting the measurement of the legacy idle mode UEsinto system information and broadcasts the system information within thecell. Here, the idle mode UE denotes the UE having no Radio ResourceControl (RRC) connection with the RNC. In the UMTS mobile communicationsystem, such informations include Sintrasearch, Sintersearch,SsearchRATm, Sprioritysearch1, and Sprioritysearch2. The roles of theseinformations are described with reference to reference numbers 321 to327 of FIG. 3b and reference numbers 331 to 335 of FIG. 3 c.

In the LTE mobile communication system, the eNB configures theinformations for supporting the measurement of the legacy idle mode UEinto the system information and broadcasts the system information withinthe cell at step 313. Here, the idle mode UE means the UE having no RRCconnection with the eNB. The system information of the LTE mobilecommunication system is capable of including Sintrasearch andSnonintrasearch informations. The roles of these informations aredescribed with reference to reference numbers 331 to 335 of FIG. 3 c.

Upon receipt of the system information, the idle mode UE of the UMTSmobile communication system performs the measurement procedure 321 to327 or 331 to 335. The UMTS system information includes the informationindicating the measurement operation to be executed. If it is indicatedto execute the UE measurement procedure of steps 321 to 327, the systeminformation includes Sintrasearch, Sintersearch, and SsearchRATminformations. If these informations are received in the systeminformation, the idle mode UE of the UMTS mobile communication systemcompares the measurement value of the radio signal of the currentserving cells with the reference threshold values received in the systeminformation. The measurement value of the radio strength of the servingcell can be the value of the received signal power to the serving cell'sreference channel or LTE mobile communication system's Reference Signal(RS) or the value of the received quality of the reference channel ofthe serving cell to the entire interference. Here, the reference channelcan be Common Pilot Channel (CPICH) of the UNITS system and ReferenceSignal (RS) of the LTE system. Also, the received signal power of thereference channel of the serving cell as the measurement can be ReceivedSignal Code Power (RSCP) of the UMTS system and the Reference SignalReceived Power (RSRP) of the LTE system. Also, as an example of themeasurement, the received signal quality of the serving cell's referencechannel to the entire interference is Ec/No of the UMTS system andReference Signal Received Quality (RSRQ) of the LTE system. The CPICHRSCP/CPICH Ec/No or RSRP/RSCP of the UMTS mobile communication systemand LTE mobile communication system are specified in the 3GPP standardTS25.215/TS36.214.

The radio signal strength measurement value of the serving cell can bemeasured as the reference channel received power of the serving cell orthe received signal quality of the serving cell's reference channel tothe entire interference, and the two measurements can be signaled asspecific values. For example, the when using the RSCP measurement valueof the reference channel of UMTS, the measurement value can be signaledas Sintrasearch1, Sintersearch2, and SsearchRATm1 values; and when usingthe Ec/No measurement value of the reference channel, the measurementvalue can be signaled as Sintrasearch, Sintersearch, and SsearchRATm.

If the Sx of the current serving cell is (equal to or) greater than theSintrasearch value as denoted by reference number 321 of FIG. 3b , theidle mode UE of the UMTS mobile communication system skips theintra-frequency (herein after the term “Intra-F” is usedinterchangeably) measurement process and, otherwise if the Sx of thecurrent serving cell is (equal to or) less than the Sintrasearch valueas denoted by reference numbers 323, 325, and 327, performs theintra-frequency measurement process. Also, if the Sx of the currentserving cell is (equal to or) greater than the Sintersearch value asdenoted by reference number 321 and 323, the idle mode UE skips theinter-Frequency (hereinafter, the term ‘Inter-F’ is usedinterchangeably) measurement process and, otherwise if Sx of the currentserving cell is (equal to or) less than the Sintersearch value asdenoted by reference numbers 325 and 327, performs the inter-Frequencymeasurement. Furthermore, if Sx of the current serving cell is (equal toor) greater than SsearchRATm value of a specific system m as denoted byreference numbers 321, 323, and 325, the idle mode UE skips Inter-RadioAccess Technology (hereinafter, the term ‘Inter-RAT’ is usedinterchangeably) measurement process and, otherwise if Sx of the currentcell is (equal to or) less than SsearchRATm as denoted by referencenumber 327, performs the inter-RAT measurement process to the specificsystem m.

The LTE and some UMTS mobile communication systems adopt priorityconcept to frequency/system in order for the idle mode UE to perform themeasurement and cell (re)selection in consideration of the prioritiesassigned to the frequencies/systems. Suppose that the current servingcell of the idle mode UE operates on frequency 2 with priority 2 andneighbor cells operate on frequency 1 with priority 1 and frequency 3with priority 3. In this case, although the radio signal strength of thecurrent serving cells is advantageous, the UE performs theinter-frequency measurement to the frequency 3 having the high priorityas compared to the current serving cell's and, if a neighbor cell havingthe channel quality greater than a predetermined threshold value on thefrequency 3, performs cell re(selection) on the frequency 3 and, if theradio signal strength of the current serving cell is advantageous, it isnot necessary to perform the inter-frequency measurement on thefrequency 1 having the low priority as compared to the frequency of thecurrent serving cell. However, if the radio signal strength of thecurrent serving cell falls below the threshold value, it becomesnecessary for the UE to perform inter-frequency measurement on thefrequency 1 and, if a neighbor cell having the radio signal strengthgreater than the threshold value on the frequency 1, performs cell(re)selection on the frequency 1.

Reference numbers 331 to 335 of FIG. 3c denote a measurement process ofthe idle mode UE in the UMTS mobile communication system and LTE mobilecommunication system adopting the frequency/system priority concept. IfSx of the current serving cell is (equal to or) greater thanSintrasearch value as denoted by reference number 331, the idle mode UEskips intra-frequency measurement and, otherwise if Sx of the currentserving cell is (equal to or) less than Sintrasearch value as denoted byreference numbers 333 and 335, performs the intra-frequency measurement.Also, if Sx of the current cell is (equal to or) greater thanSnonintrasearch (LTE) or Sprioritysearch1/Sprioritysearch2 (UMTS) asdenoted by reference numbers 331 and 335, the idle mode UE skipsinter-frequency/inter-RAT measurement process to the frequency/systemhaving the priority equal to or less than that of the frequency of thecurrent serving cell. If Sx of the current serving cell is (equal to or)less than Snonintrasearch (LTE) or Sprioritysearch1/Sprioritysearch2(UNITS) as denoted by reference number 335, the idle mode UE performsinter-frequency/inter-RAT measurement process to the frequency/systemhaving the priority to the frequency/system having the priority equal toor less than that of the frequency of the current serving cell.

However, the above-described measurement method is inefficient for theidle mode M2M/MTC device with low or no mobility. That is to say, it isinefficient to apply the measurement method designed for the legacy UEsuch as mobile phone having relatively high mobility to the idle modeM2M/MTC device having low mobility. This is because the conventionalmeasurement method makes the M2M/MTC device perform measurementoperation unnecessarily even though no movement is predicted. There istherefore a need of an efficient measurement method for the idle modeM2M/MTC device with low mobility.

DISCLOSURE OF INVENTION Technical Problem

If the measurement method of the UE having relatively high mobility isapplied to the idle mode M2M/MTC device having low or no mobilitywithout modification, this is likely to cause inefficiency. This isbecause the measurement method performs measurement forcibly even whennot movement is predicted so as to waste power. There is therefore aneed of developing an efficient measurement method for idle mode M2M/MTCdevice with low mobility. Although the description is directed to theidle mode M2M/MTC device with low mobility, the present invention isapplicable to other devices with low mobility.

Solution to Problem

In an embodiment of the present invention, a set of a limited number ofcells where mobility of idle mode M2M/MTC devices with low mobility ispredicted, and eNB/RNC generates a separate comparison value (additionalthreshold value) triggering intra-frequency/inter-frequency/inter-RATmeasurement of the idle mode M2M/MTC devices with low mobility andbroadcasts the additional threshold value in the form of systeminformation.

The idle mode M2M/MTC device with low mobility compares Sx of thecurrent serving cells with the broadcast comparison threshold value(reference threshold value) and the separate comparison value(additional threshold value) and performs, when Sx of the currentserving cell is (equal to or) less than the comparison threshold value(reference threshold value) triggeringintra-frequency/inter-frequency/inter-RAT measurement (i.e. has a valuebetween the reference threshold and the additional threshold value), theintra-frequency/inter-frequency/inter-RAT measurement to the limitednumber of the cells wherein the mobility of the M2M/MTC device ispredicted and, otherwise when Sx of the current serving cell is (equalto or) less than the separate comparison threshold value (additionalthreshold value) triggering theintra-frequency/inter-frequency/inter-RAT measurement of the M2M/MTCdevice with low mobility, the conventionalintra-frequency/inter-frequency/inter-RAT measurement.

As an efficient measurement method of the M2M/MTC devices, the M2M/MTCdevice suspends the intra-frequency/inter-frequency/inter-RATmeasurement out of data (transmission)reception-allowed period/time andperforms the intra-frequency/inter-frequency/inter-RAT measurement inthe data (transmission) reception-allowed period/time or when the data(transmission) reception-allowed period/time is arriving. Theintra-frequency/inter-frequency/inter-RAT measurement is performedcontinuously while the M2M/MTC device is in idle mode until the data(transmission) reception-allowed period ends.

According to an embodiment of the present invention, a method for a basestation to control measurements of communication devices in a mobilecommunication system includes collecting information on thecommunication devices with low mobility; configuring system informationincluding a reference threshold value and an additional threshold valuelower than the reference threshold for optimizing idle mode measurementsof the communication devices through analysis of the collectedinformation; and broadcasting the system information for thecommunication devices within a cell, wherein the additional thresholdvalue is the threshold value for performing the measurement in a limitednumber of cells in which the mobility of the mobile devices ispredicted.

Preferably, configuring system information includes analyzing thecollected information to acquire a number of communication devices, thecollected information including information on locations and number ofthe communication devices; configuring, when the number of communicationdevices is large, the system information with the reference thresholdvalue and the additional threshold value; and configuring, when thenumber of communication device is small, the system information with thereference threshold value. Preferably, collecting information on thecommunication devices comprises receiving the information on thecommunication devices with low mobility from an O&M server or MME, andthe communication devices are the communication devices betweenelectronic devices or between an electronic device and a server.

In accordance with another embodiment of the present invention, Ameasurement method of a M2M/MTC device with low mobility in a mobilecommunication system includes receiving system information including areference threshold value and an additional threshold value from a basestation; generating a measurement value by measuring strength of a radiochannel of a serving cell; and performing, when the measurement value isless than the reference threshold value and greater than the additionalthreshold value, the measurement to a small number of cells limited inmobility; and performing, when the measurement value is less than theadditional threshold value, the measurement to entire cells.

Preferably, performing the measurement includes executing, when themeasurement value is greater than the reference threshold value,measurement only to the serving cell.

Preferably, the reference threshold value and additional threshold valueare the reference threshold values for intra-frequency orinter-frequency or inter-system measurement, and performing themeasurement executing, when the reference threshold value and additionalreference threshold value are the intra-frequency threshold values, theintra-frequency measurement; executing, when the reference thresholdvalue and additional reference threshold value are the inter-frequencythreshold values, the inter-frequency measurement; and executing, whenthe reference threshold value and additional reference threshold valueare the inter-system threshold values, the inter-system measurement.

Preferably, the measurement value is one of a received signal power of areference channel of the serving cell and a received signal quality ofthe reference channel of the serving cell to entire measuredinterference.

In accordance with another embodiment of the present invention, ameasurement method of an M2M/MTC device in the mobile communicationsystem includes checking a data communication-allowed period and whethera current time is before a start of a data communication-allowed periodas much as a predetermined threshold time value; performingintra-frequency/inter-frequency/inter-system idle mode measurement onlywhen the M2M/MTC device is in idle mode for the datacommunication-allowed period and the period before the start of a datacommunication-allowed period as much as a predetermined threshold timevalue; and skipping, when the current time is not the datacommunication-allowed period or the period before the start of a datacommunication-allowed period as much as a predetermined threshold timevalue, the intra-frequency/inter-frequency/inter-system measurement.

In accordance with another embodiment of the present invention, ameasurement apparatus of a base station for M2M/MTC device communicationin a mobile communication system includes a radio resource manager whichmanages resource of a set of a limited number of cells in which mobilityof idle mode M2M/MTC devices with low mobility; a message generatorwhich generates system information including basic measurementinformation and additional measurement information for triggeringintra-frequency/inter-frequency/inter-system measurement for the idlemode M2M/MTC devices with low mobility; and a radio transceiver whichbroadcast the system information including the basic measurementinformation and additional measurement information.

In accordance with still another embodiment of the present invention, ameasurement method of a terminal for M2M/MTC device communication in amobile communication system includes a radio transceiver which receivessystem information including additional measurement informationbroadcast; and a measurement unit which compares a measurement value ofa current serving cell with the additional measurement information andperforms, when the measurement value Sx of the current serving cell isless than the additional measurement threshold value,intra-frequency/inter-frequency/inter-system measurement to a limitednumber of cells in which mobility of the M2M/MTC device is predicted.

Advantageous Effects

Through the measurement of the idle M2M/MTC devices according toembodiments of the present invention, it is possible reduce thereception time of the idle mode M2M/MTC device for measurement bylimiting the number of cell for performing the measurement or suspendingthe measurement under specific conditions, thereby conserving the signalreception power of the M2M/MTC device efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a structure of a 3GPP UMTS mobilecommunication system;

FIG. 2 is a diagram illustrating a structure of the 3GPP LTE mobilecommunication system;

FIGS. 3a to 3c are diagrams illustrating the idle mode UE managementmethod in the 3GPP UMTS/LTE mobile communication system;

FIGS. 4a to 4c are diagrams illustrating a measurement method of theM2M/MTC device with low mobility in the mobile communication systemproposed in the present invention;

FIG. 5 is a flowchart illustrating a network operation according to theembodiment of FIGS. 4a to 4 c;

FIG. 6 is a flowchart illustrating the procedure of the idle modeM2M/MTC device with low mobility according to the embodiment of FIGS. 4ato 4 c;

FIG. 7 shows another embodiment of the measurement method of idle modeM2M/MTC device in the mobile communication system proposed in the secondembodiment of the present invention;

FIGS. 8a to 8b are a flowchart illustrating the procedure of the idlemode M2M/MTC device operating as in the embodiment of FIG. 7;

FIG. 9 is a block diagram illustrating a configuration of the networkapparatus for performing the operations of FIGS. 4a to 4c and 7according to an embodiment of the present invention;

FIG. 10 is a block diagram illustrating a configuration of the M2M/MTCdevice according to the embodiment of FIGS. 4a to 4c and 7.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the present invention are described withreference to the accompanying drawings in detail. The same referencenumbers are used through the drawings to refer to the same or likeparts. Detailed description of well-known functions and structuresincorporated herein may be omitted to avoid obscuring the subject matterof the present invention.

An embodiment of the present invention proposes an efficient measurementmethod of an idle mode M2M/MTC device with low or no mobility.

In order to accomplish this, the first embodiment of the presentinvention defines a mobility set of cells in which potential mobility ofthe idle mode M2M/MTC devices with low mobility is predicted, allowseNB/RNC to configure a threshold value to triggerintra-frequency/inter-frequency/inter-RAT measurement of the idle modeM2M/MTC devices with low mobility, and broadcasts the threshold value assystem information.

The idle mode M2M/MTC device with low mobility compares the Sx of thecurrent serving cells and the broadcast comparative threshold(hereinafter, the term ‘comparative threshold’ is used interchangeablywith the term ‘reference threshold’) and the separate comparativethreshold (hereinafter, the term ‘separate comparative threshold’ isused interchangeably with the term ‘additional threshold’) and, if Sx ofthe current serving cell is (equal to or) less than the comparativethreshold (i.e. reference threshold for triggeringintra-frequency/inter-frequency/inter-RAT measurement (i.e. in the rangebetween the reference threshold and additional threshold), performs theintra-frequency/inter-frequency/inter-RAT measurement in the cellrestricting the mobility of the M2M/MTC device and, otherwise if the Sxof the current serving cell is (equal to or) less than the separatecomparative threshold (i.e. additional threshold), performs theconventional intra-frequency/inter-frequency/inter-RAT measurement.

At this time, the idle mode M2M/MTC device with low mobility has tocheck that it is the idle mode M2M/MTC device with low mobility andacquires the information that the cells restricting the mobility of theM2M/MTC device. The method for acquiring the information is to check themeasurement result on radio of the M2M/MTC device, to receive from thehigher layer in the M2M/MTC device, to receive OMA Device Management(DM) or Non Access Stratum (NAS) control message, or to map to the cellsconstituting the registered area of the idle mode (e.g. Routing Area(RA) of UMTS mobile communication system or Tracking Area (TA) of LTEmobile communication system and map the configuration implicitly. In thepresent invention, the idle mode M2M/MTC device with low mobility checksits own device type and does not rule out the other methods foracquiring the information on the restricted cells in which the mobilityof the M2M/MTC device is predicted.

In the measurement method of the M2M/MTC device according to the secondembodiment of the present invention, the M2M/MTC device skipsintra-frequency/inter-frequency/inter-RAT measurement out of the datacommunication-permitted period/time (transmission and/or receptionallowed period/time) and performsintra-frequency/inter-frequency/inter-RAT measurement in the datacommunication-permitted period/time when data communication-permittedperiod/time arrives.

The intra-frequency/inter-frequency/inter-RAT measurement is performedwhile the M2M/MTC device is in idle mode until the datacommunication-permitted period/time ends. Theintra-frequency/inter-frequency/inter-RAT measurement can be performedaccording to the measurement method of FIGS. 3a to 3c and/or the firstembodiment of the present invention or periodically in simple manner. Ifdata occurs out of the range of the data communication-permittedperiod/time, the M2M/MTC device is capable of performing idle modeintra-frequency/inter-frequency/inter-RAT measurement from thetransmission data occurrence timing. Theintra-frequency/inter-frequency/inter-RAT measurement is performedcontinuously before the M2M/MTC device switches from the idle mode tothe Radio Resource Control (RRC) connected mode. Theintra-frequency/inter-frequency/inter-RAT measurement can be implementedaccording to the method of FIGS. 3a to 3c or the first embodiment of thepresent invention or periodically in simple manner. The above embodimentcan be applied to all M2M/MTC devices without limitation to the lowmobility M2M/MTC devices.

According to the above two embodiments of the present invention, thenumber of cells to perform the measurement is restricted or themeasurement is not performed under a specific condition such that it ispossible to reduce the active time for measurement of the M2M/MTCdevice, thereby reducing power consumption of the M2M/MTC device.

FIGS. 4a to 4c are diagrams illustrating a measurement method of theM2M/MTC device with low mobility in the mobile communication systemproposed in the present invention. According to an embodiment of thepresent invention, the RSCP measurement or Ec/No measurement value (UMTSsystem) or RSRP measurement and RSRQ measurement value (LTE system) ofthe serving cell is referred to as Sx for simplicity purpose.

Referring to FIGS. 4a to 4c , reference number 401 of FIG. 4a denotes anidle mode M2M/MTC device with low mobility, reference number 402 denotesan eNB of the LTE mobile communication system, and reference number 403denotes an RNC of the UMTS mobile communication system. Here, the RNC403 transmits to the M2M/MTC device 401 the system information includingSintrasearch, Sintersearch, SsearchRATm, Sprioritysearch1,Sprioritysearch2, and SintrasearchMTC; the eNB 302 transmits to theM2M/MTC device 401 the system information including Sintrasearch,Sintersearch, and SintrasearchMTC. According to an embodiment of thepresent invention, the eNB/RNC configures SintrasearchMTC informationinto the system information along with other information described withreference to FIGS. 3a to 3c and broadcasts the system information withinthe cell.

The SintrasearchMTC is the value to be compared with the Sx of theserving cell, and thus the M2M/MTC device 401 with low mobility comparesSx of the serving cell with SintrasearchMTC and, if Sx is (equal to or)greater than SintrasearchMTC, suspends intra-frequency measurement forthe cells with the exception of a limited number of cells where themobility of the M2M/MTC device is predicted, and, otherwise if Sx is(equal to or) less than SintrasearchMTC, performs conventionalintra-frequency measurement. If the Sx is (equal to or) less thanSintrasearch as the reference threshold value for intra-frequencymeasurement, the M2M/MTC device 401 performs intra-frequency measurementto a limited number of cells where mobility of the M2M/MTC device ispredicted.

Here, the above described measurement procedure can be applied to theinter-frequency measurement method. In which case, the measurementcomparison threshold value (e.g. SintersearchMTC) for inter-frequencymeasurement of the M2M/MTC device can be transmitted in addition to theSintersearch as the measurement comparison value for inter-frequencymeasurement. The inter-frequency measurement method is identical withthe intra-frequency measurement method with the exception that theinter-frequency measurement, rather than the intra-frequencymeasurement, is performed with the conventional reference measurementcomparison threshold value for the inter-frequency measurement and theadditional measurement comparison threshold value. Such a measurementmethod can be applied to the inter-RAT measurement method. In this case,an additional measurement comparison threshold value (e.g.SsearchRATmMTC) for inter-RAT measurement of the M2M/MTC device can betransmitted in addition to SsearchRATm as the measurement comparisonthreshold value for inter-RAT measurement. The inter-RAT measurementmethod can be performed in the same manner as the intra-frequencymeasurement method with the exception that the inter-RAT measurement,rather than intra-measurement, is performed according to theconventional measurement comparison threshold value for inter-RATmeasurement and the additional measurement threshold value for M2M/MTCdevice.

In the present invention, the description is made under the assumptionof using SintrasearchMTC.

According to another embodiment of the present invention, if Sx is(equal to or) less than SintrasearchMTC, it is possible to perform theinter-frequency measurement and/or inter-RAT measurement as well as theintra-frequency measurement to the limited number of cells where themobility of the M2M/MTC device is predicted.

Here, Sintrasearch, Sintersearch, SsearchRATm, Sprioritysearch1, andSprioritysearch2 can be the information related to the normalmeasurement, and SintersearchMTC, SintrasearchMTC, SsearchRATmMTC can bethe measurement information of the M2M/MTC device with low mobility.

Although not depicted in FIGS. 4a to 4c , each system information can bebroadcast in the form of different information or value depending on themeasurement type of the serving cell which is expressed as Sx of theserving cell. For example, if the received signal power or the receivedsignal quality of the reference channel of the serving cell is used asSx, the eNB is capable of signaling the SintrasearchMTC1 andSintrasearchMTC2 as the separately applied comparison threshold values.

In the UMTS mobile communication system to whichinter-frequency/inter-RAT priory is not applied, the M2M/MTC devicehaving low mobility compares the measurement value on the radio channelof the current serving cell Sx with SintrasearchMTC. The measurementvalue Sx for the serving cell can be the received signal power of thereference channel of the serving cell or the received signal quality ofthe reference channel of the serving cell to the entire interference.Here, the received signal power on the reference channel of the servingcell can be CPICH RSCP of the UNITS mobile communication system or RSRPof the LTE mobile communication system, and the received signal qualityon the reference channel of the serving cell to the entire interferencecan be CPICH Ec/No of the UMTS mobile communication system or RSRQ ofthe LTE mobile communication system. The measurement procedure isspecified in the 3GPP standard TS25.215/TS36.214.

As denoted by reference number 421 of FIG. 4b , if Sx of the servingcell is (equal to or) greater than Sintrasearch, the M2M/MTC deviceperforms measurement for the current serving cell but not anyintra-frequency measurement. As denoted by reference numbers 423, 425,427, and 429, if Sx of the serving cell is (equal to or) less thanSintrasearch, the M2M/MTC device performs intra-frequency measurement tothe limited number of cells where the mobility of the M2M/MTC device ispredicted. As denoted by reference numbers 421 and 423, if Sx of theserving cell is (equal to or) greater than SintrasearchMTC, the M2M/MTCdevice suspends performing intra-frequency measurement for other cellwith the exception of the limited number of cells where the mobility ofthe M2M/MTC device is predicted. As denoted by reference numbers 425,427, and 429, if Sx of the serving cell is (equal to or) less thanSintrasearchMTC, the M2M/MTC device performs the normal intra-frequencymeasurement regardless of the limited number of cells where the mobilityof the M2M/MTC device is predicted. As denoted by reference number 423,the M2M/MTC device is capable of determining the conditions in which Sxof the current serving cell is (equal to or) less than Sintrasearch and(equal to or) greater than SintrasearchMTC as the condition forperforming the intra-frequency measurement to the limited number ofcells where the mobility of the me2m/MTC device is predicted.

According to another embodiment of the present invention, an additionalcomparison threshold value (e.g. SintersearchMTC) for triggeringinter-frequency/inter-RAT measurement of the M2M/MTC device with lowmobility is signaled in the form of system information and, if the Sx is(equal to or) less than Sintersearch, the M2M/MTC device performsinter-frequency measurement to the limited number of cells where themobility of the M2M/MTC device is predicted. If Sx of the currentserving cell is (equal to or) greater than SintersearchMTC, the M2M/MTCdevice does not perform inter-frequency measurement for other cells withthe exception of the limited number of cells where the mobility of theM2M/MTC device is predicted. Otherwise, if Sx of the current cell is(equal to or) less than SintersearchMTC, the M2M/MTC device performsinter-frequency measurement regardless of the limited number of cellwhere the mobility of the M2M/MTC device is predicted. If the Sx of thecurrent serving cell is (equal to or) less than SsearchRATm, the M2M/MTCdevice performs inter-RAT measurement to the system m for the limitednumber of cells where the mobility of the M2M/MTC device is predicted.If the Sx of the current serving cell is (equal to or) greater thanSsearchRATmMTC, the M2M/MTC device does not perform inter0RATmeasurement to the system m for other cells with the exception of thelimited number of cells where the mobility of the M2M/MTC device ispredicted. Otherwise, if Sx of the current serving cell is (equal to or)less than SsearchRATmMTC value, the M2M/MTC device performs inter-RATmeasurement to the legacy system m regardless of the limited number ofcells where the mobility of the M2M/MTC device is predicted. Thecondition required for the M2M/MTC device to perform the inter-frequencymeasurement to the limited number of cells where the mobility of theM2M/MTC device is predicted can be configured as the condition where theSx of the current cell is (equal to or) less than Sintersearch and(equal to or) greater than SintersearchMTC, and the conditions requiredfor the M2M/MTC device to perform the inter-RAT measurement to thelimited number of cells where the mobility of the M2M/MTC device ispredicted can be configured as the condition where Sx of the currentserving cell is (equal to or) less than SsearchRATm and (equal to or)greater than SsearchRATmMTC.

According to another embodiment of the present invention, if Sx of thecurrent serving cell is (equal to or) less than SintrasearchMTC, theM2M/MTC device performs inter-frequency measurement or Inter-RATmeasurement as well as intra-frequency measurement to the limited numberof cells where the mobility of the M2M/MTC device is predicted.

If Sx of the current serving cell is (equal to or) less thanSintrasearch, the M2M/MTC device performsintra-frequency/inter-frequency/inter-RAT measurement for the currentserving cell and the limited number of cells where the mobility ofM2M/MTC device is predicted. If Sx of the current serving cell is (equalto or) greater than SintrasearchMTC, the M2M/MTC device does not performintra-frequency/inter-frequency/inter-RAT measurement to the limitednumber of cells where the mobility of the M2M/MTC device is predictedand, otherwise if Sx of the current serving cell is (equal to or) lessthan SintrasearchMTC, the M2M/MTC device performs the conventionalintra-frequency regardless of the limited number of cells where themobility of the M2M/MTC device is predicted and performs inter-frequencyand inter-RAT measurements with Sintersearch and SsearchRATm as theconventional comparison threshold values.

In the UMTS mobile communication system and LTE mobile communicationsystem to which inter-frequency/inter-RAT priority is applied, theM2M/MTC device with low mobility compares, upon receipt of the systeminformation, the measurement value Sx of the radio channel of thecurrent serving cell with SintrasearchMTC at steps 411 and/or 413. Thereceived signal power on the reference channel of the serving cell orthe received signal quality on the reference channel of the serving cellto the entire interference can be uses as the measurement value Sx ofthe serving cell. Here, the received signal power on the referencechannel of the serving cell can be CPICH RSCP of the UMTS mobilecommunication system or RSRP of the LTE mobile communication system, andthe received signal quality on the reference channel of the serving cellto the entire interference can be CPICH Ec/No of the UNITS mobilecommunication system or RSRQ of the LTE mobile communication system. Themeasurement process is specified in the 3GPP standard TS25.215/TS36.214.

As denoted by reference number 431 of FIG. 4c , if Sx of the currentserving cell is (equal to or) greater than Sintrasearch, the M2M/MTCdevice performs measurement for the current serving cell but not anyintra-frequency measurement. As denoted by reference numbers 433, 3=435,and 437 of FIG. 4c , if Sx of the current serving cell is (equal to or)less than Sintrasearch, the M2M/MTC device performs intra-frequencymeasurement to the limited number of cells where the mobility of theM2M/MTC device is predicted. As denoted by reference number 431 and 433,if Sx of the current serving cell is (equal to or) greater thanSintrasearchMTC, the M2M/MTC device does not perform intra-frequencymeasurement for other cells with the exception of the limited number ofcells wherein the mobility of the M2M/MTC device is predicted and,otherwise if Sx, as denoted by reference number 435 and 437, is (equalto or) less than SintrasearchMTC, performs the conventionalintra-frequency measurement regardless of the limited number of cellswhere the mobility of the M2M/MTC device. As denoted by reference number433, the condition required for performing intra-frequency measurementto the limited number of cells wherein the mobility of the M2M/MTCdevice can be configured as the condition where Sx of the currentserving cell is (equal to or) less than Sintrasearch and (equal to or)greater than SintrasearchMTC.

According to another embodiment of the present invention, an additionalcomparison threshold value for triggering inter-frequency/inter-RATmeasurement of the M2M/MTC device with low mobility (e.g.SnonintrasearchMTC (LTE) or Sprioritysearch1MTC/Sprioritysearch2MTC(UMTS) is signaled as system information and if Sx of the currentserving cell is (equal to or) less than Snonintrasearch (LTE) orSprioritysearch1/Sprioritysearch2, the M2M/MTC device performsinter-frequency/inter-RAT measurement on the frequency/RAT having apriority less than that of the frequency of the current serving cellsfor the limited number of cell where the mobility of the M2M/MTC deviceis predicted. If Sx of the current serving cell is (equal to or) greaterthan SnonintersearchMTC (LTE) or Sprioritysearch1MTC/Sprioritysearch2MTC(UMTS), the M2M/MTC device does not perform inter-frequency/inter-RATmeasurement on the frequency/RAT having the priority less than that ofthe current serving cell for the cells with the exception of the limitednumber of cells where the mobility of the M2M/MTC device is predictedand, if Sx of the current serving cell is (equal to or) less thanSnonintersearchMTC (LTE) or Sprioritysearch1MTC/Sprioritysearch2MTC(UMTS), performs inter-frequency/inter-RAT measurement on thefrequency/RAT having the priority (equal to or) less than that of thefrequency of the current serving cell regardless of the limited numberof cells where the mobility of the M2M/MTC device is predicted.

According to another embodiment of the present invention, if it ispossible to perform the inter-frequency measurement or inter-RATmeasurement as well as the intra-frequency measurement to the limitednumber of cells where the mobility of the M2M/MTC device when Sx of theserving cell is (equal to or) less than SintrasearchMTC, the M2M/MTCdevice is performs, when Sx of the current serving cell is (equal to or)less than Sintrasearch, intra-frequency measurement to the limitednumber of cells where the mobility of the M2M/MTC device is predictedand inter-frequency and/or inter-RAT measurement on the frequency/RAThaving the priority lower than that of the frequency of the currentserving cell. If Sx of the current serving cell is (equal to or) greaterthan SintrasearchMTC, the M2M/MTC does not perform intra-frequency forthe cells with the exception of the limited number of cells where themobility of the M2M/MTC device is predicted and inter-frequency andinter-RAT measurements for the frequency/RAT having the priority lowerthan that of the frequency of the current serving cells and, otherwiseif Sx of the current serving cell is (equal to or) less thanSintrasearchMTC, performs conventional intra-frequency measurementregardless of the limited number of cells where the mobility of theM2M/MTC device is predicted and inter-frequency and inter-RATmeasurements for the frequency/RAT having the priority lower than thatof the frequency of the current serving cell with Snonintrasearch (LTE)or Sprioritysearch1/Sprioritysearch2 as the conventional comparisonthreshold value.

The idle mode M2M/MTC device with low mobility is capable of being awarethat it is the M2M/MTC device with low mobility and acquires theinformation on the limited number of cells where the mobility of theM2M/MTC device is predicted from the measurement result on the radiochannel of the M2M/MTC device or receives it from the higher layerentity of the M2M/MTC device or from a network node in OMA DM (DeviceManagement) or NAS (Non-Access Stratum) control message or recognizesimplicitly by configuring a registration area of the M2M/MTC device(e.g. Routing Area (RA) of UMTS mobile communication system or TrackingArea (TA) of LTE mobile communication system) and mapping theregistration area to the cells. In case of configuring the registrationarea of the idle mode M2M/MTC device and mapping the registration areato the cell implicitly, the M2M/MTC device receives the information onthe cells constituting the registration area of the idle mode M2M/MTCdevice from the network node (e.g. MME or Server). The present inventiondoes not rule out the other methods in which the idle mode M2M/MTCdevice with low mobility recognizes itself as the M2M/MTC device withlow mobility and acquires the information on the limited number of cellswhere the mobility of the M2M/MTC device is predicted.

FIG. 5 is a flowchart illustrating a network operation according to theembodiment of FIGS. 4a to 4c . FIG. 5 is a flowchart illustratingprocedure of the RNC of the 3GPP UMTS mobile communication system andthe eNB of the LTE mobile communication system.

Referring to FIG. 5, the eNB/RNC receives the information about theM2M/MTC devices with low mobility from an O&M server or MME at step 501.The information is capable of including the locations and number of theM2M devices. The location information is capable of including cellinformation and paging registration area information, and the numberinformation is capable of including the number of M2M/MTC devices. TheeNB/RNC determines whether to configure an additional measurement methodfor the idle mode M2M/MTC devices with low mobility based on thereceived information at step 511. At step 511, if there is noinformation on the number of M2M/MTC devices or the number of is smallenough to negligible and thus there is no need to optimize the idle modemanagement method for the M2M/MTC devices, the eNB/RNC configures theconventional measurement-related informations for the idle mode UE intothe system information at step 521. Otherwise, if the number of the idlemode M2M/MTC devices with low mobility is large and thus it is necessaryto optimize the idle mode management method for the M2M/MTC devices, theeNB/RNC configures the system information with additional comparisonthreshold informations (e.g. SintrasearchMTC) for the M2M/MTC device aswell as the information related to the conventional measurement for theidle mode UE at step 523. Next, the eNB/RNC broadcasts the systeminformation configured at step 525.

Although not depicted in FIG. 5, the O&M server or MME is capable oftransmitting the information on whether the idle mode measurement methodoptimization for the idle mode M2M/MTC devices with low mobility isnecessary rather than the information on the M2M/MTC devices with lowmobility.

FIG. 6 is a flowchart illustrating the procedure of the idle modeM2M/MTC device with low mobility according to the embodiment of FIGS. 4ato 4 c.

Referring to FIG. 6, the idle mode M2M/MTC device with low mobilityreceives the system information and starts idle mode measurement at step601. The M2M/MTC device determines whether the received systeminformation includes the information related to the idle modemeasurement optimization for the idle mode M2M/MTC device with lowmobility at step 611. It is assumed that the information related to theidle mode measurement of the idle mode M2M/MTC device with low mobilityis the additional comparison threshold value SintrasearchMTC for use inthe idle mode measurement of the idle mode M2M/MTC device with lowmobility. Here, the comparison threshold value SintrasearchMTC can bethe additional measurement information. If the system informationincludes no information related to the idle mode measurement for theidle mode M2M/MTC device with low mobility at step 611, the M2M/MTCdevice performs the measurement method for the conventional idle mode UEat step 621. However, if the system information includes the informationrelated to the idle mode measurement for the idle mode M2M/MTC devicewith low mobility, the M2M/MTC device measures Sx of the current servingcell at step 623. Here, the measurement value for the serving cell Sxcan be the received signal power of the reference channel of the servingcell or the received signal quality of the reference channel of theserving cell to the measured entire interference. The received signalpower of the reference channel of the serving cell can be CPICH RSCP ofthe UMTS mobile communication system or RSRP of the LTE mobilecommunication system, and the received quality of the reference channelof the serving cell to the entire interference can be CPICH Ec/No of theUNITS mobile communication system or RSRQ of the LTE mobilecommunication system. The measurement procedure is specified in the 3GPPstandard TS25.215/TS36.214.

Afterward, the M2M/MTC device compares the measurement value on theradio of the current serving cell Sx with Sintrasearch at step 631. Ifthe Sx of the current serving cell is (equal to or) greater thanSintrasearch at step 631, the M2M/MTC device performs measurement forthe current serving cell but not intra-frequency measurement at step641. Otherwise, if the Sx of the current serving cell is (equal to or)less than Sintrasearch, the M2M/MTC device performs intra-frequencymeasurement to a limited number of cells where the mobility of theM2M/MTC device is predicted at step 643. Next, the M2M/MTC devicecompares the value Sx measured on the radio of the current serving cellwith SintrasearchMTC at step 651. If Sx of the current serving cell is(equal to or) greater than SintrasearchMTC at step 651, the M2M/MTCdevice does not perform intra-frequency measurement for other cells withthe exception of the limited number of cells where the mobility of theM2M/MTC device is predicted at step 661. Otherwise, if Sx of the currentserving cell is (equal to or) less than SintrasearchMTC at step 651, theM2M/MTC device performs conventional intra-frequency measurementregardless of the limited number of cells where the mobility of theM2M/MTC device is predicted at step 663.

According to another embodiment, the condition for performing theintra-frequency measurement to the limited number of cells where themobility of the M2M/MTC device is predicted can be restricted to thecondition of Sx (equal to or) less than Sintrasearch and (equal to or)greater than SintrasearchMTC.

Although not depicted in FIG. 6, according to another embodiment of thepresent invention, an additional comparison threshold value (e.g.SintersearchMTC) for triggering inter-frequency/inter-RAT measurement ofthe M2M/MTC device with low mobility or an additional comparisonthreshold value (e.g. SsearchRATmMTC) for triggering inter-RATmeasurement can be signaled as system information. At this time, if theadditional comparison threshold value (e.g. SintersearchMTC) fortriggering inter-frequency/inter-RAT measurement, the followingoperation can be performed. If Sx of the current serving cell is (equalto or) less than Sintersearch, the M2M/MTC device performsinter-frequency measurement to the limited number of cells where themobility of the M2M/MTC device is predicted. If Sx is (equal to or)greater than SintersearchMTC, the M2M/MTC device does not performinter-frequency measurement for other cell with the exception of thelimited number of cells where the mobility of the M2M/MTC device ispredicted and, otherwise if Sx of the current serving cell is (equal toor) less than SintersearchMTC, performs the conventional inter-frequencymeasurement regardless of the limited number of cells where the mobilityof the M2M/MTC device is predicted. If the additional comparisonthreshold value (e.g. SsearchRATmMTC) for triggering inter-RATmeasurement, the following operations can be performed. If Sx of thecurrent serving cell is (equal to or) less than SsearchRATm, the M2M/MTCdevice performs inter-RAT measurement to the system m for the limitednumber of cells where the mobility of the M2M/MTC device is predicted.If Sx of the current serving cell is (equal to or) greater thanSsearchRATmMTC, the M2M/MTC device does not perform inter-RATmeasurement to the system m for the other cells with the exception ofthe limited number of cells wherein the mobility of the M2M/MTC deviceis predicted and, otherwise if Sx of the current serving cell is (equalto or) less than SsearchRATmMTC, performs inter-RAT measurement to theconventional system m regardless of the limited number of cells wherethe mobility of the M2M/MTC device is predicted. According to anotherembodiment, the condition required for performing inter-frequencymeasurement to the limited number of cells where the mobility of theM2M/MTC device is predicted can be restricted to the condition requiringthat Sx of the current serving cells is (equal to or) less thanSintersearch and (equal to or) greater than SintersearchMTC, and thecondition required for performing inter-RAT measurement to the limitednumber of cell where the mobility of the M2M/MTC device is predicted canbe restricted to the condition requiring that Sx of the serving cell is(equal to or) less than SsearchRATm and (equal to or) greater thanSsearchRATmMTC.

Although not depicted in FIG. 6, according to another embodiment, if theinter-frequency measurement or inter-RAT measurement can be performed aswell as the intra-frequency measurement to the limited number of cellswherein the mobility of the M2M/MTC device is predicted when Sx of theserving cell is (equal to or) less than SintrasearchMTC, the M2M/MTCdevice performs, if Sx of the current serving cell is (equal to or) lessthan Sintrasearch, intra-frequency, inter-frequency, inter-RATmeasurements for the current serving cell and the limited number ofcells where the mobility of the M2M/MTC device. If Sx of the currentserving cell is (equal to or) greater than SintrasearchMTC, the M2M/MTCdevice does not perform intra-frequency, inter-frequency, inter-RATmeasurements for the other cells with the exception of the limitednumber of the cells where the mobility of the M2M/MTC device ispredicted and, otherwise if Sx of the current serving cell is (equal toor) less than SintrasearchMTC, performs conventional intra-frequencymeasurement regardless of the limited number of the cells where themobility of the M2M/MTC device is predicted and performs theinter-frequency measurement and inter-RAT measurement with theconventional threshold values of Sintersearch and SsearchRATm.

The operations of the M2M/MTC device with Sintrasearch andSintrasearchMTC in the UMTS mobile communication system and LTE mobilecommunication system using inter-frequency/inter-RAT priority areidentical with the measurement method in the UMTS mobile communicationsystem to which the aforementioned inter-frequency/inter-RAT priority isnot applied. However, in case that the additional comparison thresholdvalue (e.g. SnonintrasearchMTC (LTE) orSprioritysearch1MTC/Sprioritysearch2MTC (UMTS)) for triggeringinter-frequency/inter-RAT measurement of the M2M/MTC device with lowmobility is signaled as the system information in the UMTS mobilecommunication system and LTE mobile communication system to whichinter-frequency/inter-RAT priority is applied, if Sx of the currentserving cell is (equal to or) less than Snonintrasearch (LTE) orSprioritysearch1/Sprioritysearch2, the M2M/MTC device performsinter-frequency/inter-RAT measurement to the frequency/RAT having thepriority lower than that of the frequency of the current serving cellfor the limited number of cells where the mobility of the M2M/MTC deviceis predicted. If Sx of the current serving cell is (equal to or) greaterthan SnonintersearchMTC (LTE) or Sprioritysearch1MTC/Sprioritysearch2MTC(UMTS), the M2M/MTC device does not perform inter-frequency/inter-RATmeasurement to the frequency/system having the priority less than thatof the frequency of the current serving cell for the other cells withthe exception of the limited numbe3r of cells where the mobility of theM2M/MTC device is predicted and, otherwise if Sx of the current servingcell is (equal to or) less than SnonintersearchMTC (LTE) orSprioritysearch1MTC/Sprioritysearch2MTC (UMTS), performsinter-frequency/inter-RAT measurement to the frequency/RAT having thepriority of (equal to or) less than that of the frequency of the currentserving cell regardless of the limited number of cells where themobility of the M2M/MTC device is predicted.

According to another embodiment of the present invention, if theinter-frequency measurement or inter-RAT management can be performed aswell as the intra-frequency measurement to the limited number of cellswhere the mobility of the M2M/MTC device is predicted when Sx of theserving cell is (equal to or) less than SintrasearchMTC, the M2M/MTCdevice performs, if Sx of the current serving cell is (equal to or) lessthan Sintrasearch, intra-frequency measurement to the limited number ofcells where the mobility of the M2M/MTC device is predicted andinter-frequency and/or inter-RAT measurement to the frequency/RAT havingthe priority lower than that the frequency of the current serving cell.If Sx of the current serving cell is (equal to or) greater thanSintrasearchMTC, the M2M/MTC device performs intra-frequency measurementfor the other cells with the exception of the limited number of cellswhere the mobility of the M2M/MTC device is predicted and suspends theinter-frequency and inter-RAT measurement to the frequency/RAT havingthe priority lower than that of the frequency of the current servingcell and, otherwise if Sx of the current serving cell is (equal to or)less than SintrasearchMTC, performs the conventional intra-frequencymeasurement regardless of the limited number of cells where the mobilityof the M2M/MTC device is predicted and inter-frequency and inter-RATmeasurements to the frequency/RAT having the priority lower than that ofthe frequency of the current serving cell with the conventionalcomparison threshold value of Snonintrasearch (LTE) orSprioritysearch1/Sprioritysearch2.

The idle mode M2M/MTC device with low mobility is capable of being awarethat it is the M2M/MTC device with low mobility and acquires theinformation on the limited number of cells where the mobility of theM2M/MTC device is predicted from the measurement result on the radiochannel of the M2M/MTC device or receives it from the higher layerentity of the M2M/MTC device or from a network node in OMA DM (DeviceManagement) or NAS (Non-Access Stratum) control message or recognizesimplicitly by configuring a registration area of the M2M/MTC device(e.g. Routing Area (RA) of UMTS mobile communication system or TrackingArea (TA) of LTE mobile communication system) and mapping theregistration area to the cells. In case of configuring the registrationarea of the idle mode M2M/MTC device and mapping the registration areato the cell implicitly, the M2M/MTC device receives the information onthe cells constituting the registration area of the idle mode M2M/MTCdevice from the network node (e.g. MME or Server). The present inventiondoes not rule out the other methods in which the idle mode M2M/MTCdevice with low mobility recognizes itself as the M2M/MTC device withlow mobility and acquires the information on the limited number of cellswhere the mobility of the M2M/MTC device is predicted.

FIG. 7 shows another embodiment of the measurement method of idle modeM2M/MTC device in the mobile communication system proposed in the secondembodiment of the present invention. The invention of FIG. 7 is notlimited to the M2M/MTC device with low mobility but application to allthe types of M2M/MTC devices. The M2M/MTC device performs datatransmission/reception only for predetermined period/time. For example,the data transmission/reception of a metering/meter-reading system canbe restricted, by the operator, to be performed for specific timeduration with low data traffic of communication terminal such as normalmobile phones by the operator. This is to minimize influence of the datatransmission/reception of the metering/meter-reading system to thecommunication of the terminals such as conventional mobile phone.Meanwhile, the data reception of the M2M/MTC device can be received forspecific period/time. For example, if emergency data of themetering/meter-reading system (e.g. the data alarming the electricaloverload state which may cause fire or alarming the flood caused bywater leakage) occurs, it should be allowed to transmit emergency dataimmediately. The invention of FIG. 7 can be applied to the case wherethe data transmission/reception of the M2M/MTC device is performed forpredetermined period/time or only the data reception of the M2M/MTCdevice is performed for predetermined period/time.

The M2M/MTC device 701 can be the M2M/MTC device in idle mode. The idlemode M2M/MTC device 701 does not performintra-frequency/inter-frequency/inter-RAT measurement for theperiod/time for from the data communication-allowed period/time or datareception-allowed period/time as denoted by reference number 711. Thatis, the M2M/MTC device does not performs intra-F/inter-F/inter-RATmeasurement for the period/time other than period/time in a specificthreshold time value before the start of the datatransmission/reception-allowed (period/time for receiving informationfrom the higher layer) and the period/time other than the period/time ina specific threshold time value (period/time other than first and secondperiod/time). Also, the periodic paging message reception check is notnecessary in the corresponding period/time. That is, it is not necessaryto perform intra-F/inter-F/inter-RAT measurement outside the datatransmission/reception-allowed period/time (period/time for receivinginformation from higher layer). If it is the time before the start ofdata (transmission) reception-allowed period/time of the M2M/MTC deviceas much as predetermined threshold time value (here, the predeterminedthreshold time value may be 0) as denoted by reference number 731, theM2M/MTC device starts intra-frequency/inter-frequency/inter-RATmeasurement based on the system information received from the cell. Atthis time, the predetermined threshold value can be a specific thresholdtime value, and the specific threshold value can be a fixed valuedetermined as standard or the system information configured by thesystem that is broadcast within the cell or signaled through the controlmessage dedicated to the M2M/MTC device. At this time, the RNC 703transmits to the M2M/MTC device the system information includingSintrasearch, Sintersearch, SsearchRATm, Sprioritysearch1,Sprioritysearch2, and SintrasearchMTC at step 721; and the eNB 702transmits to the M2M/MTC device the system information includingSintrasearch, Sintersearch, and SintrasearchMTC at step 723. As denotedby reference number 731 at the M2M/MTC device side, theintra-frequency/inter-frequency/inter-RAT measurement is performedcontinuously while the M2M/MTC device is in idle mode until the data(transmission) reception-allowed period/time ends. The period forperforming the intra-frequency/inter-frequency/inter-RAT measurement isidentical with the data (transmission) reception-allowed period/time ofthe M2M/MTC device (when the measurement starts in the (transmission)reception-allowed period/time) or a little longer than the data(transmission) reception period/time of the M2M/MTC device (when themeasurement starts before the start of the data (transmission)reception-allowed period/time) as much as specific threshold value). ifthe M2M/MTC device is actually (transmitting) receiving data, theM2M/MTC device transitions from the idle mode to RRC connected mode fordata (transmission) reception as denoted by reference number 733 and itis not necessary for the M2M/MTC device to perform idle mode measurementin the RRC connected mode. The intra-frequency/inter-frequency/inter-RATmeasurement of the idle mode M2M/MTC device is performed according tothe conventional measurement method of FIGS. 3a to 3c and the embodimentof FIGS. 4a to 4c of the present invention in the period/time denoted byreference number 731 or the periodicintra-frequency/inter-frequency/inter-RAT measurement can be performedsimply. If the data (transmission) reception-allowed period/time of theM2M/MTC device ends, the M2M/MTC device does not performintra-frequency/inter-frequency/inter-RAT measurement as denoted byreference number 741 and also the periodic paging message receptioncheck is not necessary.

If data to be transmitted by the M2M/MTC device occurs in theperiod/time outside the allowed data (transmission) receptionperiod/time of the M2M/MTC device as denoted by reference number 751,the M2M/MTC device receives the system information from the cell at thetime when the data to be transmitted occurs as denoted by referencenumbers 761 and 763 and performs idle modeintra-frequency/inter-frequency/inter-RAT measurement based on thereceived system information as denoted by reference number 771. Asdenoted by reference number 771, the idle modeintra-frequency/inter-frequency/inter-RAT measurement is performedcontinuously before the M2M/MTC device transitions from the idle mode tothe RRC connected mode as denoted by reference number 781. Theintra-frequency/inter-frequency/inter-RAT measurement of the idle modeM2M/MTC device can be performed with the conventional measurement methodof FIGS. 3a to 3c or the method according to the embodiment of thepresent invention that is proposed in FIGS. 4a to 4c , or the periodicintra-frequency/inter-frequency/inter-RAT measurement can be performedsimply. Once the data transmission of the M2M/MTC device ends, theM2M/MTC device does not performintra-frequency/inter-frequency/inter-RAT measurement as denoted byreference number 791 and is not necessary to perform periodic pagingmessage reception check.

FIGS. 8a to 8b are a flowchart illustrating the procedure of the idlemode M2M/MTC device operating as in the embodiment of FIG. 7. Theflowchart of the network operation in the embodiment of FIG. 7 can beapplied to the conventional network operation described with referenceto FIGS. 3a to 3c or the network operation of the embodiment of FIGS. 4ato 4 c.

Referring to FIGS. 8a to 8b , the M2M/MTC device performs registrationprocess with the UNITS mobile communication system or the LTE mobilecommunication system at step 801. After the system registration process,the M2M/MTC device determines whether the data (transmission)reception-allowed period/time information of the M2M/MTC device isacquired. The registration process with the mobile communication systemcan be the ATTACH process of the LTE mobile communication system,Routing Area Update (RAU) process of the UMTS mobile communicationsystem, the Tracking Area Update (TAU) process of the LTE mobilecommunication system. The ATTACH process starts when the terminal powerson to register the terminal with the mobile communication system,acquire IP address, and establish Packet Data Network (PDN) connection;and the RAU/TAU process is performed when the terminal registers with aspecific paging area for receiving the paging signal. The information onthe data (transmission) reception-allowed period/time of the M2M/MTCdevice is acquired from the Non-Access Stratum (NAS) control messagetransmitted by the MME or the data transmitted by a network server orthe higher layer of the M2M/MTC device (e.g. application layer). If nodata (transmission) reception-allowed period/time of the M2M/MTC deviceis configured at step 811, the M2M/MTC device performsintra-frequency/inter-frequency/inter-RAT measurement according to theidle mode measurement method depicted in FIGS. 3a to 3c or the idle modemeasurement method proposed in the embodiment of FIGS. 4a to 4c a step821. Otherwise, if the data (transmission) reception-allowed period/timeof the m2a device is configured at step 811, the M2M/MTC devicedetermines whether it is the time before the start of the data(transmission) reception-allowed period/time as much as predeterminedthreshold time (e.g. N1 seconds) at step 831. The predeterminedthreshold time value can be transmitted form the network to the M2M/MTCdevice or a fixed value defined in the standard. If it is the timebefore the start of the data (transmission) reception-allowedperiod/time as much as the threshold time at step 831, the M2M/MTCdevice receives the system information of the cell and starts idle modeintra-frequency/inter-frequency/inter-RAT measurement based on thesystem information at step 841. Next, the M2M/MTC device repeats steps843 and 851 to continue the idle modeintra-frequency/inter-frequency/inter-RAT measurement until the data(transmission) reception-allowed period/time ends. If it transitionsfrom the idle mode to the RRC connected mode in the middle of the data(transmission) reception-allowed period/time, the M2M/MTC device detectsthis at step 843 and suspends the idle modeintra-frequency/inter-frequency/inter-RAT measurement for the RRCconnection mode at step 853. If the data (transmission)reception-allowed period/time expires during the repetition of steps 843and 851, the M2M/MTC device detects this at step 843 and suspends theidle mode intra-frequency/inter-frequency/inter-RAT measurement and thepaging message reception at step 853. Theintra-frequency/inter-frequency/inter-RAT measurement of the idle modeM2M/MTC device can be performed according to the measurement method ofFIGS. 3a to 3c or the measurement method proposed in the embodiment ofthe present invention which is depicted in FIGS. 4a to 4c or a periodicintra-frequency/inter-frequency/inter-RAT measurement can be performedfor the simplicity sake.

If it is not the time before the start of the data (transmission)reception-allowed period/time as much as the threshold time at step 831,the M2M/MTC device performs the operations of step 861 and later. Atthis time, as far as no data occurs in the range out of the data(transmission) reception-allowed period/time, the M2M/MTC devicesuspends the idle mode intra-frequency/inter-frequency/inter-RATmeasurement while performing steps 861 and 871. Also, there is no needof the paging message reception check. If data to be transmitted by theM2M/MTC device occurs in the range out of the data (transmission)reception-allowed period/time of the M2M/MTC device, the M2M/MTC devicedetects this at step 861 and performs the idle modeintra-frequency/inter-frequency/inter-RAT measurement based on thesystem information received from the cell since the time when the datato be transmitted has occurred at step 873. Afterward, if the datatransmission does not finish in the idle mode state while performingsteps 881 and 891, the M2M/MTC device continues the idle modeintra-frequency/inter-frequency/inter-RAT measurement. However, if theM2M/MTC device transitions to the RRC connected mode or the datatransmission finishes at step 881, the M2M/MTC device suspends the idlemode intra-frequency/inter-frequency/inter-RAT measurement at step 893.The intra-frequency/inter-frequency/inter-RAT measurement of the idlemode M2M/MTC device can be performed according to the measurement methodof FIGS. 3a to 3c or the measurement method proposed in the embodimentof the present invention which is depicted in FIGS. 4a to 4c or aperiodic intra-frequency/inter-frequency/inter-RAT measurement can beperformed for the simplicity sake.

FIG. 9 is a block diagram illustrating a configuration of the networkapparatus for performing the operations of FIGS. 4a to 4c and 7according to an embodiment of the present invention. FIG. 9 shows anexemplary configuration of the RNC of the 3GPP UMTS mobile communicationsystem and eNB of the LTE mobile communication system.

Referring to FIG. 9, a wired transceiver 901 provides an interfaceresponsible for wired connection with MME, SGSN, and O&M server for wireline communication. The radio resource manager 911 analyzes theinformation received by the wired transceiver 901 and allocates radioresource. The message generator 921 generates a message indicating theallocated message, and the radio transceiver 931 transmits the generatedmessage to the cell or the M2M/MTC device. The base station apparatusaccording to an embodiment of the present invention includes a radioresource manager 911 for managing the resource of a set of a limitednumber of cells where the mobility of the M2M/MTC devices with lowmobility is predicted, a message generator 921 for generating the systeminformation with the normal measurement information of the idle modeM2M/MTC devices with low mobility and additional measurement triggeringintra-frequency/inter-frequency/inter-RAT measurement, and a radiotransceiver 931 for broadcasting the system information including thebasic measurement information and additional measurement information.

A description is made of the operations for transmitting the systeminformation from the base station system structured as shown in FIG. 9to the M2M/MTC device according to an embodiment of the presentinvention. If the wired transceiver 901 connected to the MME or SGSNreceives the information on the number of M2M/MTC devices with lowmobility per location or the information on the idle mode measurementconfiguration of the M2M/MTC device, the radio resource manager 911analyzes the information received by the wired transceiver 901 toconfigure the parameter values for the measurement of the M2M/MTC devicewith low mobility, the message generator 921 generates a messagecarrying the system information including the parameter valuesconfigured by the radio resource manager 911, and the radio transceiver931 broadcasts the generated message in order for the M2M/MTC devices toreceive the message within the cell.

FIG. 10 is a block diagram illustrating a configuration of the M2M/MTCdevice according to the embodiment of FIGS. 4a to 4c and 7.

Referring to FIG. 10, if the information on its type of the M2M/MTCdevice with low mobility and the information on a small number of cellsthat might be limited by the mobility are acquired, the informationanalyzer and manager 1021 analyzes and manages the received information.If the system information acquired by the radio transceiver 101 includesthe information related to the idle mode measurement for the M2M/MTCdevice with low mobility, the information analyzer and manager 1021analyzes the received information and delivers the analysis result tothe scheduler. The scheduler 1011 controls the measurement unit 1041 toperform measurement operation. If the (transmission) reception-allowedperiod/time information is acquired from the higher layer 1031 orthrough higher layer message, the M2M/MTC device analyzes and managesthis information by means of the information analyzer and manager 1021and delivers the analysis result to the scheduler 1011. The schedulercontrols the measurement unit 1041 to perform the measurement operation.

While embodiments of the present invention have been shown and describedin the specification and drawings to illustrate and explain the presentinvention, it should be understood that the present invention is notlimited to these specific embodiments. That is, it is obvious to thoseskilled in the art that various changes and modification may be madetherein without departing from the technical concept of the invention.

What is claimed is:
 1. A method by a terminal in a wirelesscommunication system, the method comprising: receiving, from a corenetwork entity, a message including time value for the terminal;starting a timer corresponding to the time value; prohibiting a taskassociated with an idle mode in case that the timer expires, the taskincluding monitoring a paging message; identifying whether a mobileoriginated data is pending; and performing the task associated with theidle mode in case that the mobile originated data is pending.